The present invention relates to power operated mixing and flow control valves. Valves of this type are employed where it is desired to mix fluid from a heated and unheated source to produce a fluid mixture of preselected temperature and to control the discharge rate of the mixed fluid. In particular, power operated valves of this type are employed in domestic laundry appliances to control the filling of the fluid in the tub, particularly those of the type having a tub with a motor driven agitator. In the typical household washing machine a power operated valve has attached to one inlet thereof the household cold water line and to a second inlet thereof the line from the hot water heater. Upon energization from the washing machine program timer, the power operated valve assembly admits either cold or hot or a mixture of the hot and cold water to the washing machine tub.
In certain appliance operating programs it is desired to provide for a initially higher flow rate during a portion of the program, followed by a substantially lower flow rate during other portions of the program, and to provide for changing the flow rate during the program independently of the mixing control of the incoming hot and cold water. Although it has been proposed to use separate, individual power operated valves fluidically in parallel with the mixing valve, such an arrangement is prohibitively costly from a manufacturing standpoint. It is also power-consuming, in that a plurality of valves must be operated at a given time to provide the desired temperature and flow rate of the incoming fluid.
Thus it has been desired to provide a power operated valve assembly which provides control for mixing separate incoming streams of hot and cold water and to provide a plurality of discharge rates for the fluid mixture in a compact simple and easy to manufacture arrangement which consumes a minimum of power during the various modes of operation.